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Apr 11th, 2014
21.2% record efficiency for industrial PERC silicon solar cell with improved screen-printed contacts
The Institute for Solar Energy Research Hamelin (ISFH) being an associated institute of the Leibniz University of Hanover increases the conversion efficiency of industrial silicon solar cells with screen-printed metal contacts from typical 17.5% to 19.5% to a record value of 21.2%, as confirmed by an independent measurement of the Fraunhofer ISE CalLab.
The efficiency of the cell realized at the Institute for Solar Energy Research Hamelin (ISFH) has been confirmed by an independent measurement of the Fraunhofer ISE CalLab.
Fig 1: The 21.2%-screen printed world record solar cell in the hands of Dr. Thorsten Dullweber (ISFH).
21.2% is the highest efficiency reported so far worldwide for industry typical silicon solar cells with screenprinted metal contacts. Two technological improvements enable the record conversion efficiency. First, the cell front side is metallized using an advanced five busbar design and a dual print process, which reduces the contact finger width to 46 μm and hence significantly reduces the shadowing loss. This advanced printing process was optimized at ISFH in collaboration with DEK Solar, using their Eclipse screen printing platform and precision screens and stencils. Leading-edge silver pastes supplied by Heraeus were used for printing the front-side grid. Second, the local rear metal contacts were screen-printed with an improved aluminum paste provided by DuPont Microcircuit Materials using an optimized contact geometry with narrower contact lines. Beyond these innovations, the silicon solar cell applies an AlOx/SiNy- passivated rear side (PERC) and typical industrial processes, in particular a homogeneously phosphorus diffused emitter and a 156 x 156 mm2 large boron-doped Czochralski (Cz) silicon wafer.
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